Tuesday 17 August 2004 07.40 EDT
First published on Tuesday 17 August 2004 07.40 EDT

One morning last month, when I was in America attending the Democratic convention in Boston, I stole away from politics and the noisy city and drove the short distance out to the solitude of the woods surrounding Walden Pond.

Some readers, especially if they are Americans, will immediately know where this column is heading. Many other readers, especially if they are British, may not. For surprisingly few people in this country now seem to read the works of Henry David Thoreau, whose Walden was first published 150 years ago this month and has rarely been out of print since.

A few books have had the capacity to change the way that people look at the world. It has been striking to read on the Guardian letters page recently, how fervently so many feel this way about Robert Tressell's The Ragged Trousered Philanthropists. It is not a view I share. For me, Tressell's so-called socialist novel is one of the most over-rated books on the shelves.

Walden, on the other hand, first did the trick for me when I was a student and continues to work an effect whenever I return to it. No book asks us more insistently to think about ourselves and to examine our claims to be free creatures. I am certainly not alone in my admiration for it. Thoreau's reflection on his solitary two years living on the shores of Walden Pond was a book that once captured the imagination of Tolstoy and of Gandhi. He is still one of the icons of the environmentalist movement. And he remains one of the necessary reference points for all those who, however intermittently and imperfectly, ask themselves the question: How should life be lived?

This was indeed the question that took Thoreau to Walden Pond in March 1845 from his nearby home in historic Concord - a town that also numbered Emerson, Hawthorne and Alcott among its inhabitants and can thus boast comfortably the most concentrated literary associations in the United States. "I went to the woods because I wished to live deliberately," Thoreau wrote in one of Walden's most celebrated passages, "to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived."

He proceeded to do the thing for which he is now remembered. Borrowing an axe, Thoreau began to cut down some white pine on the shores of Walden Pond, before the winter ice had melted in the cove that now bears his name. By the early summer, he had built himself a small hut, and on Independence Day 1845 - nice touch that - he moved in. For the next two and a bit years he was to live there alone, tending for himself, observing, listening, thinking and chronicling, until he emerged from the woods to rejoin the world in September 1847.

It was truly a back-to-nature, return-to-the-simple-life experiment. But Thoreau did not live as a hermit, and you only need to visit Walden Pond to grasp that, even then, such a thing was not really practicable. Even in the 1840s, the lake and the woods that surround it were hardly in the back of beyond. Sometimes, Thoreau would walk into town - Concord is not far distant - and at other times friends would come to the woods to seek him out. Throughout his sojourn, Thoreau could hear not just the call of the loon and the owl, or the shuffling of the woodchuck, but, as he describes, the more workaday noises of a railway that ran close by.

Undoubtedly, Thoreau loved the natural world that he describes so beautifully. But he should not be seen as some misty-eyed 19th-century new-age shaman, mumbling and chanting about the wonder of creation or how everything is connected. His real subject is not nature but the life of human beings. It might be more illuminating to see Walden as a high-minded Victorian forerunner of a reality TV endurance trial, like Survivor or I'm a Celebrity Get Me Out of Here.

The book in which he details his experience is gratifyingly impossible to pigeonhole. Walden is part diary, part natural history, part philosophical treatise. One of his friends dubbed Thoreau a "poet-naturalist", but he was also a historian, an economist, a reporter and - above all - a rebel. Prudish, austere and stubborn Thoreau may well have been, but Walden is really the original alternative manifesto. The critic Brooks Atkinson described it as "the practical philosophy of a rebellion against the world's cowardly habits of living".

In the 60s, when I first read Walden, Thoreau was sometimes dubbed the world's first dropout. It might be more accurate, these days, to regard him as the godfather of the gap year. But the real point about Thoreau, and particularly about Walden, is that he challenges us to take life seriously, to look difficult choices in the face and to try to lead a grounded and integrated life.

Which is why, I think, Walden is a book for all time, and in some ways why it is a book especially for ours. Thoreau thought life in the 1840s was intolerably false and pressured. That is why he went out to discover what mattered to him in his hut by Walden Pond. But what on earth would the man who wrote about "this restless, nervous, bustling, trivial 19th century" have found to say about the 21st, so much more restless, so much more nervous, so much more bustling and so very much more trivial?

"Why should we be in such a desperate haste to succeed," is how Thoreau puts it, "and in such desperate enterprises? If a man does not keep pace with his compan ions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away."

Even to spend a couple of hours by Walden Pond, with the mighty modern city, its materialism and its noise just 20 minutes away down the turnpike, is to grasp something of the message of the book that Thoreau drafted here. It is to be reminded of how easy it is to be carried along unthinkingly by modern life, and at what cost, without asking the questions one should always ask and without taking responsibility for that failure. To read Thoreau is to learn a little humility.

"How many a man has dated a new era in his life from the reading of a book?" Thoreau writes. Reading The Ragged Trousered Philanthropists obviously has that effect for some. I just wish that such readers would face the fact that people who believed what Tressell believed spent much of the 20th century murdering millions of people and enslaving countless millions of others in a system which did not work.

I'm not sure that Thoreau has the answers to all of life's mystery and complexity either. But I know few writers who speak more plainly about the shortcomings of modern hedonism and materialism. What is more, I do not think that anyone has ever murdered a single person in the name of the worldview that Thoreau expounded. And, frankly, that's good enough for me.